Exterior wall openings are often poorly insulated, and represent major sites of potential heat loss from homes, garages, and other structures, especially during cold winter months. Heat loss from exterior wall openings results in increased annual heating costs for home owners and increased household energy consumption.
Insulating properties of a material are often measured in terms of thermal resistance. R-value is a commonly used measure of thermal resistance. A typical exterior wall may have an R-value of around R-20. Wall openings such as windows or doors, on the other hand, are typically less than R-7. Thus, exterior wall openings represent an important source of heat loss from homes, apartments, offices, garages, and other structures.
Exterior wall openings are often glazed or unglazed panels that can allow air and/or light into a room, and/or provide access to and from the room. Building code standards accept reduced insulation standards for wall openings because typical windows and doors have an insulative capacity which does not extend much beyond ˜R-7 value (windows) or ˜R-11 or 14 value (doors).
Exterior wall openings typically offer surfaces which are exposed to sunlight for at least part of the day. In some cases, window and door design and placement can allow sunlight to enter homes during the day, serving as a minor source of heat. Sunlight is also sometimes harnessed for heat using solar thermal panels or collectors such as those described in Canadian Patent Application No. 2,393,273 and/or PCT Publication No. WO 98/57101.
Solar-Thermal panels are often placed on a wall or roof exposed to winter sunshine to provide heat. However, the available solar thermal panels do not provide insulation to exterior wall openings such as doors and windows, for example.
Wall sections of a building envelope also lose heat, and often feature large surface areas which are typically covered with siding, brick, or other building materials which do not provide much benefit in terms of energy capture from sunlight. Wall sections of a building envelope may thus be modified with solar energy collectors such as, for example, a solar powered furnace as described in U.S. Pat. No. 8,757,143.
An alternative, additional, and/or improved insulating and/or heat generating structure is desirable.